SiC (silicon carbide) is superior in heat resistance and mechanical strength to existing semiconductor materials such as Si (silicon) and GaAs (gallium arsenide), and has good resistance to radiation. In addition, it is easy to perform valence control of electrons and holes by doping an impurity. Moreover, SiC has a wide band gap (for example, single crystal 6H-SiC has a band gap of about 3.0 eV, and single crystal 4H-SiC has a band gap of 3.26 eV). Therefore, it is possible to realize a large capacity, high-frequency property, dielectric property, and environmental resistance which cannot be realized by existing semiconductor materials. SiC is receiving attention and is expected as a semiconductor material for a next-generation power device.
As a method of producing (growing) single crystal SiC of this type, known are a method in which single crystal SiC is grown by a sublimation and recrystallization method using a seed crystal, and that in which, in the case of a high temperature, epitaxial growth is conducted on a silicon substrate by using a chemical vapor deposition method (CVD method), thereby growing single crystal cubic SiC (.beta.-SiC).
In the above-described conventional production methods, however, the crystal growth rate is as low as 1 .mu.m/hr. Furthermore, the sublimation and recrystallization method has a problem in that pin holes which have a diameter of several microns and which pass through the crystal in the growing direction remain at about 100 to 1,000/cm.sup.2 in a growing crystal. Such pin holes are called micropipe defects and cause a leakage current when a semiconductor device is fabricated. These problems block a practical use of single crystal SiC which has superior characteristics as compared with other existing semiconductor materials such as Si and GaAs as described above.
In the case of the high-temperature CVD method, the substrate temperature is as high as 1,700 to 1,900.degree. C., and it is required to produce a high-purity reducing atmosphere. Therefore, the method has a problem in that it is difficult to conduct the method from the view point of installation. Furthermore, the method has another problem in that, because of epitaxial growth, the growth rate is naturally limited.